*{
    margin: 0;
    padding: 0;
}
.box{
    width: 100vw;
    height: 100vh;
    display: grid;
    grid-template-columns: 200px 1fr;
    grid-template-rows: 70px 1fr;
    grid-template-areas: 
    "a b"
    "a c ";
}
aside{
    grid-area: a;
    background-color: #f7f6f2;
}
aside li{
    list-style: none;
}
header{
    grid-area: b;
    background-color: #3e3d43;
}
main{
    grid-area: c;
    background-color: palegreen;
    display: grid;
    grid-template-columns: 1fr;
    grid-template-rows: 40px;
} 
main table,td{
    border: solid 1px black;
    text-align: center;
}